I was also dissapointed at this conecpt, because it seemed like a replicated and better version of Humankind at first glance. However, I eventually came to believe this is far more intriguing than having the same Civilization play the entire game. So, this is one of the most anticipated parts for me.

However, if some other suggestions don't bother you...

Arabia: The Rashidun Caliphate seems too late for the Antiquity era. Although my knowledge of the Arabian Peninsula's pre-Islamic history is limited, I think there may be more suitable countries.

Aztec: As far as I know, Leaders don't belong to certain Civilizations this time. So maybe Olmec can make an appearance? (since a leader does not necessarily need to represent their Civilization)

Egypt: The Mamluk Sultanate is intriguing enough, in my opinion. Saladin's shadow obscures Baybars' greatness as a ruler and commander.

Germany: The Holy Roman Empire also seems too late for Antiquity. How about the Goths, Vandals, or...

Korea: Thank you for bringing up Gojoseon. Unfortunately, though, there aren't many records about this kingdom, so it would be tough to create its unique components. So, I would like to suggest Silla for Antiquity, Goryeo or Joseon for Exploration, and Korea for the Modern era.

Persia: Yes, I strongly believe it is now the right time for the appearance of the Timurid Empire. However, the Middle Ages saw the rise and fall of other Persian dynasties, including the Samanid and Saffarid.

Italy: A fascinating option would be Venice. However, it was always a little disappointing that Florence, the Renaissance's birthplace, never appeared as a playable Civilization. On the other hand, I think modern Italy would be intriguing. :)

Russia: The Duchy of Moscow also seems too late... :(

• I see your point about the Radishun Caliphate being too late to fit into the Antiquity Age. A good alternative from the pre-Islamic era might be Nabatea, the kingdom that built Petra. It was a bit farther north, but it was in the same general region.

• My first choice actually was the Olmecs, but then I realized that the Mayans were already confirmed to be appearing, so I went with them instead.

• The Mamluk Sultanate is a good alternate option, especially since we just had Saladin in Civ 6. I mostly went with the Ayyubid Sultanate due to being more familiar with it.

• As much as it pains me to say it, you are probably right that the Holy Roman Empire is too late for the Antiquity Age, and that either it or Prussia has to go. Between the two, I would probably sacrifice Prussia, push the Holy Roman Empire to the Exploration Era, and have the Vandals in the Antiquity Age.

• A Silla-Joseon-Korea progression makes sense to me.

• There were a lot of Persian empires to choose from, and the Timurids seemed like the best option for the Exploration Era.

• Florence would be a great option too, especially with the expansion of the advisors system with actual historical figures. Having Leonardo Da Vinci or one of the Medicis as advisors would be a must.

• Perhaps the Scythians could represent Antiquity Age Russia? They obviously didn’t inhabit the exact same region, but they do use a number of Russian cities in Civ 6.

@Darth Cumulonimbus Thank you for the kind reply. Yes, I believe that just three eras are insufficient, ...... but hold on. Who am I talking about a game starts with H, which I've never played before...? :/

By the way, would it be okay if I wrote a similar post on this? Since you're the first in this field, I think I should get your permission before trying.

@Safiye Choson I would not be surprised if a DLC ends up adding a Future Age of some kind, like the Gathering Storm expansion did for Civ VI. Hopefully, it would be significantly more fleshed out though, given how few ages are in the game to begin with.

As for you making your own version of this concept, go right ahead! To be honest, I was actually sort of hoping that this post would prompt others to share their own ideas.